Viewing file:  iscloseto.py (2.21 KB) -rw-r--r--
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import six
from hamcrest.core.base_matcher import BaseMatcher
from math import fabs
__author__ = "Jon Reid"
__copyright__ = "Copyright 2011 hamcrest.org"
__license__ = "BSD, see License.txt"
def isnumeric(value):
"""Confirm that 'value' can be treated numerically; duck-test accordingly
"""
if isinstance(value, (float, complex) + six.integer_types):
return True
try:
_ = (fabs(value) + 0 - 0) * 1
return True
except ArithmeticError:
return True
except:
return False
return False
class IsCloseTo(BaseMatcher):
def __init__(self, value, delta):
if not isnumeric(value):
raise TypeError('IsCloseTo value must be numeric')
if not isnumeric(delta):
raise TypeError('IsCloseTo delta must be numeric')
self.value = value
self.delta = delta
def _matches(self, item):
if not isnumeric(item):
return False
return fabs(item - self.value) <= self.delta
def describe_mismatch(self, item, mismatch_description):
if not isnumeric(item):
super(IsCloseTo, self).describe_mismatch(item, mismatch_description)
else:
actual_delta = fabs(item - self.value)
mismatch_description.append_description_of(item) \
.append_text(' differed by ') \
.append_description_of(actual_delta)
def describe_to(self, description):
description.append_text('a numeric value within ') \
.append_description_of(self.delta) \
.append_text(' of ') \
.append_description_of(self.value)
def close_to(value, delta):
"""Matches if object is a number close to a given value, within a given
delta.
:param value: The value to compare against as the expected value.
:param delta: The maximum delta between the values for which the numbers
are considered close.
This matcher compares the evaluated object against ``value`` to see if the
difference is within a positive ``delta``.
Example::
close_to(3.0, 0.25)
"""
return IsCloseTo(value, delta)
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